Because she was there from the start, when you were just a naïve kid who didn't know what all the jokes in “10 Things I Hate About You” meant.

She knew you before you got cool and still managed to like you (even if she won't let you live down the time you crapped your pants at summer camp).

Having a big sister is like having an older best friend who lets you unplug the cord when you're losing to her in video games. She won't get jealous of you when you're succeeding at life, and she won't judge you when you're having an off day.

Instagram/ Kendall Jenner

Not only does she make family photos look more full and lively, she also makes your life more full and lively. Here's why having a big sister is, by far, the greatest gift your parents ever gave you:

1. She let you in on the “grown-up stuff”

If it wasn't for her, you would have never known what those sexual innuendos in “Clueless” meant. Or what shady family business was really going down in the kitchen after dinner (it wasn't dessert).

Sometimes, though, she used this to torture you — like the time she 89 percent convinced you that you were adopted. Thanks, betch.

2. She helped build your character

Those times when her friends came over and she would close the door on you were really character-building moments. And if your mom forced them to include you in Hide and Seek, it always ended badly when they purposely never found you.

Remaining silently hidden in a cramped linen closet for over two hours really teaches you a lot about personal limitations.

3. You can give each other real talk

“Take off my f*cking shoes now you sheisty ho before you stretch them out with your size 10 orangoutang feet.”

4. She helps you score job opportunities

Having a big sister means having an extended network of her well-developed professional connections.

Her friends are likely to be your immediate supervisors, so you'll be ahead of the game when submitting for job opportunities. Plus, she always knows of amazing internship openings way ahead of everyone else.

5. She'll give you honest fashion advice

Since you're a representation of both you and your sister's genetic ability, you can best believe she won't let you leave the house looking like “Clarissa Explains It All.”

And if she's in a particularly good mood, she might even offer her own closet for inspiration. Be careful not to ruin it though — she's got a lot of blackmail on you.

6. She broke-in your parents

The fact that you stayed out past curfew getting drunk and having sex with your college boyfriend just doesn't seem that big of a deal in comparison to your sister's runaway phase.

Her wild slip-ups prepared your parents well for your turn at growing up.

7. You can project your anger onto her

While most friends would hate you for this, your sister has no choice but to continue loving you even after you've irrationally thrown your mobile at her face.

8. She's the responsible one

You can count on her to remember to buy mom's birthday gift (or mom's actual birthday for that matter). And as parent-appointed babysitter, she's used to looking out for you.

You still haven't learned how to function properly at family gatherings because she's always assuming sibling responsibilities.

9. She lets you crash her apartment

Sibling sleepovers are the best because you get to use all her fancy makeup and bath products and make a mess of her kitchen and order OnDemand like a psycho. It's kind of like the next best thing to a snow day.

10. She drove you everywhere in high school

And she made you look cooler because you were riding with seniors. Plus, the teachers already knew her and loved her and gave her A's and, therefore, loved you as well.

11. She keeps her mouth shut when your boyfriend sneaks into your bedroom

…Or when you come home really high and/or drunk and continue to raid the pantry.

12. She upgrades the family name

If you're always being referred to as “so-and-so's little sister” then it's important that she sets a good example. But not too good — you're still in competition for who's the hotter sibling.

13. She doubles your stock

Whether it's your collective Pokemon card collection or having an extra wardrobe, having a sister means having double of everything. Sharing, on the other hand, is another issue…

14. She's the person you copy

She taught you everything you know, from how to tell off that b*tch at recess to curling your hair. You even copied her old homework and reused her book reports.

You actually liked receiving her hand-me-downs because you secretly always thought she was cooler than you.

15. She's your life guru

Your big sis gives the most insightful advice because, as someone who has your same blood, she actually cares about what happens to you.

16. She's the only person who can commiserate about your family with you

Sure, you can vent about your family to your friends, but it's totally uncool for them to retaliate with something like, “Yeah your mom sucks.” Your sister, however, completely gets it and has full license to make fun of your mom's constant neuroticism.

17. She's your unconditional supporter

When no one else will buy your candy for charity or laugh at your antics, your big sis steps in. She's been rooting for you since birth (despite trying to undermine your early childhood development).

18. She's someone to play house with

Literally, when you were kids. And now figuratively, as she'll have you over for dinner and pack your lunch of leftovers for the next day.

19. Your parents let you do “bonding” activities

“Mom, Dad we need money to go out to dinner together because Melissa just had a bad day at work and we're brainstorming where we'll ship you guys when you finally decide to retire.”

20. She gives you solid advice on men

“Touch one of my sleazy guy friends and I'll kill you.”

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Laura Argintar is the Senior Women's Writer at Elite Daily. Listed among her achievements are performing stand-up, graduating from the U of M and writing for her favorite publications. LARG enjoys covering women’s topics, watching celebrities ...

Laura Argintar is the Senior Women's Writer at Elite Daily. Listed among her achievements are performing stand-up, graduating from the U of M and writing for her favorite publications. LARG enjoys covering women’s topics, watching celebrities ...